Extensible strand sideframe conveyor



FORWARD Nov. 4, 1958 M. G. CARLSON ET AL 3,

EXTENSIBLE STRAND SIDE-FRAME CONVEYOR Filed May 7, 1957 2 Sheets-Sheet 1 Ill FORW4RD HOLD REVERSE MEANS ONE-WAY LOCK/N6 INVENTOR. Melvin G. Carlson BY Charles T. Ogden 7 41M ATTORNEP ACCUMULATOR Nov. 4, 1958 Filed May 7, 1957 M. CARLSON ET AL EXTENSIBLE STRAND SIDEFRAME CONVEYOR 4-T v I 45 57 59 49 54 o 2 Sheets-Sheet 2 INVENTOR.

Melvin G. Carlson' Charles T. Ogden ATTORNEY United States Patent 0,

EXTENSIBLE STRAND SIDEFRAME CONVEYOR Melvin G. Carlson, Oak Lawn, and Charles-T. Ogden, Chicago, Ill., assignors to Goodman Manufacturing Company, Chicago, 111., a corporation of Illinois Application May 7, 1957, Serial No. 657,549 20 Claims. (Cl. 198-139) vention is concerned, is shown in Craggs and McCann co-pending application Serial No. 549,603 filed November 29, 1955. Generally speaking, this type of conveyor includes a head section, a tail section spaced from the head section, a belt trained between the sections and having a load carrying reach movable in a direction from.

the tail section toward the head section, strand means comprising one or more wire ropes trained along a course between the sections, belt support means comprising troughing roller assemblies carried by the strand means and along which the load carrying reach runs, and means for moving the tail section forward or backward while correspondingly paying out or taking up the strand means at the tail section and while also correspondingly paying out or taking up the belt from a storage loop usually located in the head end section.

The wire ropes which are used to support the load carrying reach of the belt are usually wound on storage drums carried by the tail section. The drums are normally driven by a hydraulic motor supplied with fluid under pressure by a pump. As long as the pump is running, pressure will be supplied to the motor, which will tend to drive its drum and maintain tension in the corresponding rope proportional to the pressure supplied. To maintain the rope tension when the tail' is stationary and the pump is inoperative, as for example through a non-Working shift or over a week-end, some kind of ratchet, dog or locking means may be provided between the tail section and the drum. The above-described structure is now prior art, having been disclosed in the patent and patent application referred to.

A problem has arisen in the use of this equipment which has been solved by the present invention. The tail end section is usually located closely behind a shuttle car, loading machine, or continuous miner for instance, when it is employed in underground coal mines. Occasionally, this equipment, which is all very heavy, and which is constantly being moved back and forth, will overrun in the backward direction and strike the tail section, displacing it backward a few inches or even a few feet. If this happens to a tail section having two-way strand locking means such as shown by the above Serial No. 549,603, in which the strand means is locked against movement in both directions and must be'manually released prior to tramming in either direction, the entire strand means would go slack and drop the conveyor on the floor.

The present invention is concerned with (a) strand 2,858,934 Patented Nov. 4, 1958 of the locking means concurrently with operation of the tramming means for the tail section, (b) a special one- Way strand locking means enabling the tensioning means to wind the strand means in, automatically, whenever the tail section is displaced backward, but locking the strand means against pay-out except when released concurrently with forward tramming, (c) a control system in which the strand locking means is automatically released with operation of the tramming mechanism, (d) a one-way locking arrangement for holding the strand means against uncontrolled pay-out from the tail section but enabling the strand means to be wound, automatically, through the locking means, and (e) such a one-way locking arrangement, combined with an auxiliary power source, for example a hydraulic accumulator, which is effective to wind the strand even when its primary power source fails.

An object of the present invention is to render a strand tensioning hydraulic motor means capable of automatically winding up strand means when the tail is moved backward, whether the pump comprising the primary power source for the strand tensioning means is in operation or not. cifically, carried out by providing locking means for the winding drum in the form of a ratchet wheel connected for rotation with the drum and a pawl biased against the ratchet teeth so the pawl and ratchet wheel lock the drum against unwinding but permit winding. Thus, the pump,

urging the drum in the winding direction, would drive the drum in a winding direction any time the tail section is trammed or displaced backward. Alternatively, hedging against the possibility that the pump might be inoperative at a time when needed, a hydraulic accumulator may be provided as an auxiliary power source.

Other objects and advantages will be apparent from the description taken in connection with the drawings in which:

Figure 1 is a side view of an extensible strand sideframe conveyor illustrative of the type with which the present invention is concerned Figure 2 is a diagrammatic view of a portion of the hydraulic tensioning mechanism on the tail section, showing particularly one form of tramming and rope tensioning mechanism which may be applied to the tail section of Figure 1 to carry out the present invention;

Figure 3 is a detailed view of the mechanical driving arrangement for winding and storing strand means on the tail section;

Figure 4 is a view of Figure 3 taken along the line 33; and

Figure 5 is a modified form of one-way locking means.

Like parts are referred to by like reference characters throughout the figures of the drawings.

Referring now more particularly to the drawings, Figure 1 shows a head section H and a tail section T with strand means S'extending between the sections and supported at intervals by stands 21, 22, 23. The strand means in the present case may comprise a pair of wire ropes, each of which is wound on a drum 24 on the tail section. Each strand or rope S is guided about a pair of sheaves 26, 27 located on the rear of the tail.

The head and tail sections carry reversing pulleys 28, 29 about which a belt 31 is 'orbitally movable with a load carrying reach 32 moving from T to H and a return .reach 33 moving in the opposite direction. The reach 32 is supported on troughing assemblies 34 which are suspended from the strand means and the return reach 33 is supported on rollers 36 carried by the rope support stands. The head and tail sections are mounted, for mobility, on crawlers 37 and 38 respectively, it being understood that suitable driving means for the crawlers In the present case, this object is spe-- a 37 will be provided; driving means for the crawlers 38 is shown in Figure 2.

To supply additional belt as needed to compensate for forward movement of the tail T, a multiple loop L is provided in the lower run adjacent the head. The loop is trained between a set of idlers 39, 39 mounted on a carriage 41 fixed to the support 21. A movable carriage 42, with pulleys 43, 43 runs back and forth along a pair of horizontal rails 44 which extend forwardly from the head. A rope 46 is fastened at one end to the movable carriage 42 and at its opposite end it is wound about a motor operated winch or tensioning motor indicated by the numeral 47 which applies a predetermined tension to the rope 46 and pays it out or takes it up in accordance with the extended length of the conveyor.

Referring now to Figures 2, 3 and 4 in which the present invention is illustrated in detail, a fluid motor pump 47 is mounted on an end plate 48 which in turn is fixed as by cap screws 49 to a gear housing 51. The latter forms part of the frame for the tail section T. A motor shaft 52 has a driving pinion 53 meshed with a gear 54 on shaft 56 rotatably supported in bearings 57, 58 carried by the housing 51. The shaft 56 carries a worm 59 meshed with a worm wheel 61 on a shaft 62 which carries a pinion 63 fixed as by a key 64. The pinion 63 is meshed with a driven gear 66 mounted on a shaft 67 which carries the winding drum 68 about which the strand or rope means S is wrapped. Roller or ball bearing means 69 is provided to rotatable support the shaft 67 in the housing 51. As seen in Figure 4, the housing 51 is split into two sections held together by bolts 50.

Referring now particularly to Figure 4 which shows one-way locking means comprising an important feature of the present invention, a ratchet wheel 71 is fast to shaft 56 by means of a key 72, the same key employed for the gear 54. A dog or pawl 73 is pivoted at an intermediate portion thereof on a rod 74 carried by an inner extension 76 of the housing 51. The lower (Fig. 4) end of the pawl has an extension 77 engaged by a piston 78 movable back and forth in a bore 79 of a cylindrical insert 81 held in place by flange and bolt means 82, 83. O-ring seals 84 and 85 are employed between the piston and bore in the one case and between the cylinder and housing in the other case. A pressure line 86 is fastened by means of a coupling 87 into the flanged portion 82 and provides communication with an outside operating source.

An upper extension 88 of the pawl is formed to engage stop surfaces 89 on the ratchet wheel teeth 91. As I will be observed, the end surface 92 of the extension 88 is formed to engage the surface 89 of each of the teeth 91. Both engaging surfaces are canted so as to be slightly non-radial with respect to the center of shaft 56 to facilitate clockwise, disengaging movement of the pawl with respect to the ratchet wheel. In the specific example, this non-radial inclination is shown as being three degrees and this has been found to operate successfully in practice. By contrast, if the surfaces 89, 92 were radial with respect to the center of the shaft 56, the surface 92 would tend to heel against the other surface instead of breaking cleanly away from it. The upper pawl extension 88 is provided with a transverse nub 93 for retaining the inner end of a compression spring 94 seated against a cap 96 threadedly engaged with the housing 51.

Thus, in operation, it will be seen that the spring 94 urges the pawl counterclockwise into locking engagement with the ratchet wheel 71; and pressure applied through the tube 86 urges the pawl in a clockwise direction, against the bias of the spring.

Referring now particularly to the overall hydraulic circuit which is schematically shown in Figure 2, there are two pumps and comprises the primary hydraulic power source therefore, pump 98 which is employed for the tramming circuit and pump 99 which is used for the strand tensioning circuit. Both pumps draw from a tank (designated T). A line 102 conducts fluid to a tramming control valve 103. A relief valve 105 is provided for line 102 and likewise a relief valve 116 is provided for pressure line 117. These relief valves protect the pumps 98 and 99.

The valve 103 has an inlet port 104, a tank port and a pair of output lines 106, 107 connect respectively with ports in the valve body which alternately function as output and return ports. The interior of the valve is provided with a bore having a multi-spool spindle 107a formed by cutting grooves 108, 109 and 111. The spindle is held in the position shown in Figure 2 by a spring centering mechanism 112 and there is a handle 113 movable between Forward, Hold, and Reverse positions as indicated. The Hold position (Fig. 2) permits the pressure of pump 98 to be diverted through groove 108, direct to tank. Thus no substantial pressure is built up in line 102 and therefore no back pressure is communicated through line 86 to the piston 78 sufficient to overcome the bias of the spring 94.

To tram forward, the spindle 107a is moved upward (Fig. 2). This closes ofi access to tank through the groove 108 and diverts the operating fluid past check valve 114, through groove 111 into line 107, through the tramming motor 115, back through line 106, groove 109 and out to tank through port 110.

The reverse tramming operation would be substantially the same. Groove 108 again would be blocked causing pressure to be diverted through groove 109, line 106, motor 115, line 107, groove 111 and out to tank through port 110.

During either forward or reverse actuation, the back pressure in line 86 will build up to the point where it will displace the piston 78 far enough to disengage the pawl, against the bias of spring 94, so as to free the ratchet wheel to permit the drum 24 to rotate in either winding or unwinding directions. Referring now to the portion of Figure 2 which illustrates another important feature of the present invention, the pressure line 117 is in two parts, separated by the three-way valve 118 which in the present case is shown turned to divert the output of pump 99 to tank. The alternate position is to connect the two portions of line 117 to feed pressure direct to the motor 47 and on to tank through line 119.

A control line 121 is connected into the pressure line 117 and communicates with a normally closed blocking valve 122, urged by spring 123 to the normal position shown in Figure 2. An outlet line 124 connects the blocking valve through a relief valve 126 to tank. The relief valve 126 will be set at a lower pressure than that of the main relief valve 116. Thus, when pressure is introduced to the blocking valve beneath the piston 127 to raise the groove 128 into communication with lines 121 and 124, the pressure in line 117 will be determined by the lower relief valve setting of 126. This determines the back pressure which is applied to the motor 47.

When the tail section T is trammed in a forward direction, rope will be payed off of the drums 24. (It will be understood that in the present case there are two drums 24 and two sets of crawler tracks 38 on the tail section, with corresponding duplication of controls). When the drums 24 are rotated in this direction to pay off strand means, the gearing 53-66 will all be backdriven so as to drive the motor 47 as a pump. The pump will discharge into the pressure line 117. It is at this stage that it is desired to open the line 117 to the lower pressure relief of valve 126. Hence the blocking valve 122 will be connected through line 129 to line 107 which is pressurized during forward movement of the crawlers. This particular arrangement involving the operation of the low pressure relief valve 126 is described in more detail in Melvin G. Carlson co-pending application Serial No. 587,266 filed May 25, 1956.

An important feature, cooperating with locking means shown in Figures 4 or 5, is the 130 connected into line 117 through line 131, on the motor side of a check valve 132. The accumulator comprises a secondary or auxiliary hydraulic power source for the strand tensioning means. The accumulator may the one-way be of the usual type, here being illustrated as having a piston 133 and a spring pressure line 117.

The accumulator, thus, effectively maintains a cushion of pressure between the motor 47 and the check valve 132, urging the motor in the direction'to wind its corresponding drum 24.

Use and operation is as follows:

During a normal operation, when the tail T is stationary, parts will be in the position shown in Figure 2. Fluid from pump 98 will be passing, without substantial back pressure, through the valve 103 to tank. Likewise fluid from pump 99 will be passing through the valve 118, without substantial back pressure, to tank. It would not be necessary to turn the three-way valve 118 to the Figure 2 position, but it would be easier on the pump 99 where the tail is to stand for long periods of time with pump running. The showing of valve 118 is, for simplicity, a manually operated valve but in actual practice would preferably be an automatically operable unloading valve but since this comprises no part of the present invention, it is shown here in its simplest form. As shown in Figure 2, the tension in the strand means S will urge the ratchet wheel 71 in a counterclockwise direction and be held immobile by the pawl 73.

To tram forward, the valve 118 willfirst be turned to interconnect the two parts of pressure line 117 thereby pressurizing the motor 47 and urging it in a winding direction. This urgence provides the tension later required in the strand means after the ratchet wheel is subsequently unlocked. This unlocking is carried out automatically in response to the movement of the spindle 107a to forward position whereupon the back pressure in line 86 moves the piston 78 to release the pawl. As the 134 bucking pressure from the tail section is trammed forward, the ratchet wheel 71 is rotated in a counterclockwise direction, the motor 47 being driven as a pump and discharging fluid at relatively low pressure through the valve 126 as above-described. If, instead of tramming forward from the Figure 2 position, the tail is trammed backward, this is initiated by first turning the valve 118 to interconnect the portions of line 117. This pressurizes the motor 47 in a direction to urge the ratchet wheel 71 in a clockwise direction. Then, movement of the spindle 107a to reverse position starts the crawlers tramming in that direction and simultaneously releases the pawl. As the pawl and ratchet mechanism are so constructed as to permit the ratchet to rotate in a clockwise direction anyway, even with the pawl engaged, disengagement of the pawl by the piston 78 during backward tramming is not strictly necessary, except that the pawl, being spring-pressed into engagement with the teeth of the ratchet wheel,-would make an undesirable tapping or hammering noise. Actually, if desired, or if a quiet type of one-way locking mechanism were employed, the line 86 could be connected into line 107, as indicated in broken lines as line 8'6a.

For an arrangement in which the connection 86a might be used, so as to uncock the pawl 73 only on forward tramming, and yet avoid noisy clicking of ratchet teeth against the pawl, the ratchet wheel 71 may be replaced by the alternate form shown in Figure 5 which incorporates an overrunning or one-way clutch in its construction. It includes an inner race member 7112, an outer, toothed race member 71a, with sprags 150, 150 held between the races on a spring retainer 151. Here, the sprags are set so that clockwise rotation of the inner race 71b (corresponding with unwinding rotation of the drum 68) is transmitted to the outer race 71a, and then blocked by the pawl 88. But, counterclockwise rotaaccumulator tion of 71b (corresponding to winding) is permitted by the sprags, the outer race 71a remaining stationary.

Now, referring again to the Figure 2 position, and as an illustration of the advantageous operation of the ratchet type one-way rope drum locking means and the accumulator, it will be understood that the accumulator will be charged with pressure from the last prior operation of the valve 118. Under this condition, the pump 99 is completely ineffective to pressurize the motor 47 because of the pump output being diverted to tank. Now, assume a mining machine inadvertently strike the tail section T and displaces it backward. If there were no provision for automatically taking up the slack so produced in the rope, the whole conveyor would sag toward the ground and perhaps even be dropped entirely to the ground. In the present case, the accumulator serves as an auxiliary source of pressure constantly urging the ratchet wheel 71 in a clockwise direction (the winding direction) and, since the pawl 73 is disposed in a position to permit rotation in that direction, the slack will be taken out of the ropes practically instantaneously so that no damage would be done to the belt. The importance of this safety feature will be appreciated when it is understood, in many cases, that the tail section T is subjected to backward displacement quite often and any time reoperations.

While the invention has been described in terms of an embodiment which it has assumed in practice, the scope of. the invention should not be deemed to be limited by the precise embodiment herein shown, such other embodiments being intended to be reserved especially as they fall within the scope of the claims here appended. It will be apparent that the invention described here may be practiced, in some cases, without employing the accumulator 130, if the primary power source 99 is extremely reliable.

We claim:

1. In an extensible strand sideframe conveyor having a tall section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movablein a direction aligned with said course while varying the length of strand means extending therefrom to change the effective length of the conveyor, the improvement comprising: strand tensioning means carried by said tail section including a fluid motor operably connected with said strand means and effective to tension said strand means by pulling said strand means .toward said tail section responsive to pressure applied to said motor, a source of fluid under pressure, a pressure line between said motor and source, an accumulator communicating with said pressure line and chargeable with fluid under pressure by said source and functioning as an alternate pressure source for said motor, one-way locking means acting between the tail section and the strand means locking the strand means against relative movement from the tail section while maintaining the strand means free for relative movement means by pulling the strand means toward the tail section an amount corresponding to said backward movement of the tail section.

2. In an extensible strand sideframe conveyor having a' tail section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said.

tail section, said tail section being movable in a direction aligned with said course While varying the length of strand means extending therefrom to change the effective length of the conveyor, the improvement comprising: strand tensioning means carried by said tail section including a fluid motor operably connected with said strand means and effective to tension said strand means by pulling said strand means toward said tail section responsive to pressure applied to said motor, a source of fluid under pressure, a pressure line between said motor and source, an accumulator having a communicating connection with said pressure line and chargeable with fluid under pressure by said source and functioning as an alternate pressure source for said motor, check valve means in said pressure line between said source and said connection effectively holding pressure between said motor and said accumulator in event said source is ineffective to supply said pressure line, one-way locking means acting between the tail section and the strand means locking the strand means against relative movement from the tail section while maintaining the strand means free for relative movement toward the tail section; whereby, when the tail section is stationary, the locking means will maintain belt-supporting tension in the strand means if said source is ineffective to supply fluid to said pressure line; and whereby further, if the tail section is moved backward at a time when said source is ineffective to supply fluid to the pressure line, the accumulator will supply fluid under pressure to the motor to maintain belt-supporting tension in the strand means by pulling the strand means toward the tail section an amount corresponding to said backward movement of the tail section.

3. In an extensible strand sideframe conveyor having a tail section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of said strand means extending therefrom to vary the effective length of the conveyor, the improvement comprising: strand tensioning means carried by said tail section comprising a winding member about which said strand means is wrapped, a fluid motor, a driving connection between the motor and the winding member, means for controlling the movement of said winding member including oneway locking means operable to and from a locked condition in which said winding member is locked against rotation in an unwinding direction while remaining free for rotation in a winding direction, a source of fluid under pressure, a pressure line connecting said motor to said source, a pressure accumulator having a connection with said pressure line for communication with said motor, and means preventing back flow from said connection to said source; whereby winding pressure is maintained on said motor by the accumulator when said pressure source is ineflective thereby enabling said motor to Wind in strand means and maintain belt-supporting tension in said strand means during backward movement of the tail section.

4. In an extensible strand sideframe conveyor, the combination of claim 3 including means for releasing said locking means at times to enable forward movement of said tail section accompanied by unwinding of strand means from said winding member to increase the effective length of the conveyor.

5. In an extensible strand sideframe conveyor, the combination of claim 4 including means for tramming said tail section forward to increase the efiective length of the conveyor, and means operable responsive to forward actuation of said tramming means for releasing said locking means.

6. In an extensible strand sideframe conveyor having a tail section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while paying out or winding in said strand means to vary the effective length of the conveyor, tramming means actuatable to move said tail section in a forward direction for increasing the effective length of said conveyor, the improvement comprising: strand tensioning means carried by said tail section comprising a winding member about which said strand means is wrapped, a fluid motor, a driving connection between the motor and the winding member, one-way locking means associated with said winding member and operable to and from a locked condition in which said winding member is locked against rotation in a direction to unwind strand means but is free for rotation in a direction to wind strand means, means for releasing said locking means responsive to actuation of said tensioning means for forward movement of said tail section, a source of fluid under pressure, a pressure line connecting said motor to said source, a pressure accumulator having a connection with said pressure line for communication with said motor and functioning as a secondary pressure source for said motor, and means preventing back flow from said connection to said source; whereby winding pressure is maintained on said motor by the accumulator even when said pressure source is ineffective so as to wind in strand means and maintain belt-supporting tension thereon during backward movement of the tail section.

7. In an extensible strand sideframe conveyor having a tail section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable forward or backward in a direction aligned with said course while paying out or winding in said strand means to vary the effective length of the conveyor, tramming means actuatable to move said tail section forward or backward in said direction the improvement comprising: strand tensioning means carried by said tail section comprising a winding member about which said strand means is wrapped, a fluid motor, a driving connection between the motor and the winding member, one-way locking means associated with said winding member and operable to and from a locked condition in which said winding member is locked against rotation in a direction to unwind strand means but is free for rotation in a direction to wind strand means, means for releasing said locking means responsive to actuation of said tramming means for either forward or backward movement of said tail section to increase or decrease the effective length of the conveyor, a source of fluid under pressure, a pressure line connecting said motor to said source, a pressure accumulator having a connection with said pressure line for communication with said motor and functioning as a secondary pressure source, and means preventing back flow from said connection to said source; whereby winding pressure is maintained on said motor by the accumulator even when said pressure source is ineffective so as to wind in strand means and maintain belt-supporting tension thereon during backward movement of the tail section.

8. In an extensible strand sideframe conveyor having a tail section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable forward or backward in a direction aligned with said course while respectively paying out or winding in said strand means to vary the effective length of the conveyor, the improvement comprising: strand tensioning means carried by said tail section comprising a winding member about which said strand means is wrapped, a fluid motor, a driving connection between the motor and the winding member, an element rotatably driven with said winding member, one-way locking means for said element effectively locking said member against rotation in a direction for paying out strand means while enabling rotation of said member in a direction for winding strand means, a source of fluid under pressure, a pressure line connecting said motor to said source, a pressure accumulator having a connection with said pressure line for communication with said motor and functioning as an auxiliary pressure source, and means preventing back fiow from said connection to said source; whereby winding pressure is maintained on said motor by the accumulator even when said pressure source is ineifective so as to wind in strand means and maintain belt-supporting tension thereon during backward movement of the tail section.

9. In an extensible strand sideframe conveyor having a tail section with belt-supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while paying out of winding in said strand means to vary the effective length of the conveyor, the improvement comprising: strand tensioning means carried about said tail section comprising a winding member about which said strand means is wrapped, a fluid motor, a driving connection between the motor and the winding member, a ratchet wheel rotatable with said Winding member, a pawl, means biasing said pawl into engagementwith said wheel efiectively locking said member against rotation in a direction for paying out strand means while enabling rotation of said member in a direction for winding strand means, a source of fluid under pressure, a pressure line connecting said motor to said source, a pressure accumulator having a connection with said pressure line for communication with said motor and functioning in efiect as an auxiliary pressure source for said motor, and means preventing back flow from said connection to said source; whereby winding pressure is maintained on said motor by the accumulator even when said pressure source is ineffective so as to wind in strand means and maintain belt-supporting tension thereon during backward movement of the tail section.

10. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the efiective length of the conveyor, means for tramming said tail section, tram control means for actuating said tramming means for movement along said course, and strand tensioning means carried by said tail section eifective to apply a predetermined tension to said strand means; the improvement comprising: strand locking means carried by said tail section effective to lock movement of said strand means relative to the tail section, means biasing said locking means toward a locked condition, releasing means for unlocking said locking means, and means for automatically synchronizing the operation of said releasing means substantially concurrently with the operation of said tram control means.

11. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from'said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the efiective length of the conveyor, means for tramming said tail section, tram control means for actuating said tramming means for movement along said course, and strand tensioning means carried by said tail section effective to apply a predetermined tension to said strand means; the improvement comprising: strang locking means carried by said tail section effective to lock movement of said strand means relative to the tail section, means biasing said locking means toward a locked condition, and means for automatically releasing said locking means responsive to actuation of said control means.

12. The combination of claim 11 in which said tram' control means includes means actuatable to move said tail section in a forward direction while extending said strand means to increase the effective length of the con- Veyor, and means for releasing said locking means automatically responsive to forward actuation of said tram control means.

13. The combination of claim 11 in which said tram control means includes means actuatable to move said tail section in a backward direction While contracting said strand means to decrease the effective length of the conveyor, and means for releasing said locking means automatically responsive to reverse actuation of said tram control means.

14. The combination of claim 11 in which said tram control means includes means selectively actuatable to move said tail section in a forward or reverse direction while respectively extending or contracting said strand means to increase or decrease the effective length of the conveyor, and means for releasing said locking means automatically in response to either forward or reverse actuation of said tram control means.

15. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the effective length of the conveyor, means for tramming said tail section, tram control means for selectively actuating said tramming meansfor forward and backward movement along said course, and strand tensioning means carried by said tail section effective to apply a predetermined tension to said strand means; the improvement comprising: one-way locking means carried by said tail section effective to lock said strand means against extending movement from the tail section while maintaining the strand means free to contract toward the tail section.

16. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the effective length of the conveyor, means for tramming said tail section, tram control means for selectively actuating said tramming means for forward and backward movement along said course, and strand tensioning means carried by said tail section elfective to apply a predetermined tension to said strand means; the improvement comprising: one-Way locking means carried by said tail section effective when in locked condition to lock said strand means against movement from the tail section while maintaining the strand means free to move toward the tail section, means biasing said locking means toward said locked condition, and means for automatically releasing said locking means from said locked conditions, against said biasing means, responsive to actuation of said control means to move said tail section.

17. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the effective length of the conveyor, means for tramming said tail section, tram control means operable for selectively actuating said tramming means for forward backward movement along said course, and strand tensioning means carried by said tail section effective to apply a predetermined tension to said strand means and comprising a winding member about which said strand means is wrapped, and power means urging said winding member in a winding direction; the improvement comprising: an element rotatably driven with said winding member, one-way locking means for said element effectively locking said member against rotation in a direction for paying out strand means while enabling rotation of said member in a direction for winding strand means.

18. The combination of claim 17 including means for releasing said locking means to enable rotation of said winding member in a direction to pay ofl strand means.

19. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the effective length of the conveyor, means for trarnming said tail section, tram control means operable for selectively actuating said trarnming means for forward and backward movement along said course, and strand tensioning means earned by said tail section elfective to apply a predetermined tension to said strand means and comprising a winding member about which said strand means is wrapped, and power means urging said winding member in a winding direction; the improvement comprising: a ratchet wheel rotatable with said winding member, a pawl, means biasing said pawl into engagement with said wheel eflectively locking said member against rotation in a direction for paying out strand means while enabling rotation of said member in a direction for winding strand means, and means for releasing said pawl from said ratchet wheel automatically responsive to actuation of said tram control means.

20. In an extensible strand sideframe conveyor having a tail section with belt supporting strand means extending from said tail section, said strand means being trained along a course and fixed at a location remote from said tail section, said tail section being movable in a direction aligned with said course while varying the length of strand means extending therefrom to vary the effective length of the conveyor, fluid operated motor means for trarnming said tail section, tram control valve means operable to direct fluid under pressure to said motor means for moving said tail section along said course, and strand tensioning means carried by said tail section effective to apply a predetermined tension to said strand means and including a winding member about which said strand means is wrapped, and power means urging said winding member in a winding direction; the improvement comprising: a toothed ratchet wheel rotatable with said winding member, a pawl movable into and out of engagement with teeth on said ratchet wheel, means biasing said pawl into engagement with said teeth effectively locking said winding member against rotation in a direction for paying out strand means while enabling rotation of said member in a direction for winding strand means, and cylinder means engageable with said pawl to disengage it from said ratchet wheel when the cylinder means is pressurized, and a fluid connection between said tram control. valve means and said cylinder means efiective to disengage said pawl and release said winding member for unwinding operation responsive to operation of said tram motor means.

Patterson May 22, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 'No', 233583934 November 4, 1958 Melvin G, Carlson. et al.

pears in the -printed specification It is herebfi certified that error ap rrection and that the said Letters of the above "numbered patent requiring co Patent should read as corrected below.

read tail column 9, line 19, for

Column 6,- line 41, for "tall" d strand "about" read by line '71, for "strang" rea Signed and sealed this 10th day of February 1959.,

(SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Oflicer 

